Marmion (25) won his 13th international cap last weekend, but it was his first start in the Six Nations for Ireland and he played a pivotal role in their brilliant victory over England at Aviva Stadium.
“All you can do is make the most of every opportunity you have there,” says Lam. “He has learned a lot from Conor Murray. He has been in that environment. You could see he was so comfortable,” he added.
“Sometimes he has been Murray’s stunt double, when Conor has had niggles, Kieran has done all the training.
“But that gives him confidence. He was training, being a part of it, building relationships with guys around him, to the point where he was extremely comfortable.
“That is what Marmion showed at the weekend, and that is what everyone is commenting about. He just slipped in and did the job.
“You might not be playing but there is probably 100 half-backs that would like to be in that environment, and he is getting that run. You always have to keep chipping away until you get the chance. But if your chance comes don’t blow it.”
Lam departs Connacht at the end of the season, when he will hook up with Bristol. But he says Irish rugby is on a perfect footing going forward.
“Four strong provinces, there is a conveyor belt of talent coming through. The U-20s are doing well, the women are doing well. Irish rugby is in a great spot. At the weekend there easily could have been a Grand Slam. But it highlighted that we are in a healthy place.
“This whole period has been good. It’s no coincidence, there was a bit of doom and gloom last year with the other provinces.
“But everyone is doing well. You look at Scannell, Conway coming on the scene, Tiernan, then you look across at Leinster and the guys that they are bringing through with Byrne and O’Loughlin, Jack Conan.
“Irish rugby is going to be strong for a while. And to be in the top four in the world is massive. It’s great to be a part of it.”